This invention relates to a cyclone separator roof and, more particularly, to a roof for such a separator for separating solid fuel particles from gases discharged from a combustion system or the like.
Conventional cyclone separators are normally provided with a monolithic external refractory wall and roof which are abrasion resistant and insulative so that the outer casing runs relatively cool. Typically, these walls and roofs are formed by an insulative refractory material sandwiched between an inner hard refractory material and an outer metal casing. In order to achieve proper insulation, these layers must be relatively thick which adds to the bulk, weight, and cost of the separator. Also, the outer metal casing of these designs cannot be further insulated from the outside since to do so could raise its temperature as high as 1500.degree. F. which is far in excess of the maximum temperature it can tolerate.
Cyclone separators having water steam cooled walls are also known in the art. Cyclone separators using water-steam cooled walls reduce heat losses and minimize the need for internal refractory material. By doing so, these separators also reduce the bulk, weight, and cost of the separators, and these separators reduce the need for refractory-lined ductwork and expansion joints between the cyclone separator and the furnace and heat recovery sections. The roofs of these water-steam cooled cyclone separators have been formed using a metal outer casing with an inner refractory lining and using water-steam cooled tubes. The roofs formed using a metal outer casing with an inner refractory lining suffer from the deficiencies mentioned above with respect to conventional cyclone separators.
Roofs formed using water steam cooled tubes have been formed as separate roof tube circuits and have also been formed from the tubes of the walls of the outer cylinder, by bending the tubes radially inwardly towards the inner cylinder. Examples of such separator roofs are provided by U.S. Pat. No. 4,615,715, U.S. Pat. No. 4,746,337, U.S. Pat. No. 4,880,450, and U.S. Pat. No. 4,904,286, all owned by assignee Foster Wheeler Energy Corporation. Roofs formed by water-steam cooled tubes work well, but such roofs increase the fabrication cycle, are less flexible from an erection standpoint, and are relatively expensive.